linux-kernel - Re: [PATCH 0/50] Basic scheduler support for automatic NUMA balancing V7

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Message-ID: <5233D09F.6040307@oracle.com>
Date:	Sat, 14 Sep 2013 10:57:35 +0800
From:	Bob Liu <bob.liu@...cle.com>
To:	Mel Gorman <mgorman@...e.de>
CC:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Rik van Riel <riel@...hat.com>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
	Ingo Molnar <mingo@...nel.org>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Linux-MM <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/50] Basic scheduler support for automatic NUMA balancing
 V7

Hi Mel,

On 09/10/2013 05:31 PM, Mel Gorman wrote:
> It has been a long time since V6 of this series and time for an update. Much
> of this is now stabilised with the most important addition being the inclusion
> of Peter and Rik's work on grouping tasks that share pages together.
> 
> This series has a number of goals. It reduces overhead of automatic balancing
> through scan rate reduction and the avoidance of TLB flushes. It selects a
> preferred node and moves tasks towards their memory as well as moving memory
> toward their task. It handles shared pages and groups related tasks together.
> 

I found sometimes numa balancing will be broken after khugepaged
started, because khugepaged always allocate huge page from the node of
the first scanned normal page during collapsing.

A simple use case is when a user run his application interleaving all
nodes using "numactl --interleave=all xxxx".
But after khugepaged started most pages of his application will be
located to only one specific node.

I have a simple patch fix this issue in thread:
[PATCH 2/2] mm: thp: khugepaged: add policy for finding target node

I think this may related with this topic, I don't know whether this
series can also fix the issue I mentioned.

-- 
Regards,
-Bob
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